1. Field of the Invention
The present invention relates to a method and apparatus for preparing book covers for application to a preformed book block such as produced in the well known "perfect binding system" or similar book binding system. More particularly the present invention relates to an apparatus and continuous process for preparing preprinted precut book covers with an independent attachment member which functions as a fastener between the cover spine and the book block spine. The independent attachment member may take different forms but in the preferred form of the invention comprises a novel product of manufacture in the form of a compressed flexible sleeve or tube which connects the two spine areas but maintains them separated for ease of opening while providing maximum strength in the binding and in the connection between the cover and book block. The novel attachment member, which is formed from a single thickness adhesive-impervious technical paper, comprises a continuous, flattened double-walled strip with an overlap longitudinal joint in one wall. The apparatus and method, which includes the on-line formation of the attachment member, operates at extremely high speeds, is exceptionally reliable and thus may be coupled with a perfect binding system or similar binding system as in-line equipment allowing production rates even exceeding those possible with existing binding systems.
In its broadest sense the present inventive concept relates to the preparing of individual blanks, fed seriatim, with continuous formation, application and bonding of a web or tubular attachment member extending along a predetermined section of the moving blank and subsequent separation of the blanks by severing the continuously applied web or tubular member at high speeds.
2. Description of the Prior Art
Methods have been proposed and developed in the prior art for solving the problems encountered in book binding systems such as the well known "perfect binding system" introduced to North America in the late 1880's. As presently developed, the perfect bind system is used to produce mainly soft-cover books such as the well known paper backs including catalogues, phone directories, text books, technical manuals and some periodicals. In this system, the spine of the book block, comprising multiple signatures bound together, is usually glued onto the spine portion of a soft cover over its entire length and width. In some cases the cover is also glued over a certain distance from the back edge of the block onto the first and last leaf of the book block so as to obtain a stronger fastening between the cover and the block. The spine of a book made in this way is rather rigid and the book opens poorly and is thus difficult to read. The spines of such books are readily broken and the first and last leaves of the book block tend to be detached when the leaves are forced open. The term " mousetrapping" is applied in the art to the tendency of perfect bound soft-cover books of the type described to snap shut and resist lying flat on a surface for reading. This problem is well recognized with text books, instruction manuals and the like which must be held or weighted to maintain the open position in use.
Soft-cover book bindings have been devised in the prior art for solving the mousetrapping problem. One such binding utilizes a support layer in the form of a narrow strip or flat, single thickness ribbon, usually of cloth or crepe, glued to the entire spine portion of the book block and to a portion of the first and last leaf of the block. The cover, soft or hard, is then glued to the support layer, usually by strips of glue in the area of the back edges of both the first and last leaf of the block, leaving the spine of the cover separated from the book block spine. Typical of this structure is the U.S. Pat. No. 4,299,410 to Eero Jukola. Attempts have been made to automate the manufacture of this type of binding so as to be adaptable to use in perfect binding equipment, but such attempts have not produced satisfactory results. Although preassembled covers are produced by feeding a continuous web of support material to separately fed covers, the web is cut into discrete lengths and aligned and registered within the confines of the cover with no tails. Speed and reliability of such a system allow only for off-line production. The preassembled covers are stockpiled and later fed from a "batch" to the perfect bind equipment. Additionally, "side gluing" devices are essential and must be added to the perfect binding equipment to attach the preformed covers to the book block. Although such an approach may provide an adequate economic alternative in competition with more expensive hard-cover bindings, it is not adaptable to or competitive with mass production of paper back books and hence has not received wide acceptance in the industry.
U.S. Pat. Nos. 951,436 and 998,283 to C. R. Duryea and C. R. Duryea et al respectfully and U.S. Pat. No. 4,547,000 to Pentti Sallinen disclose further prior art methods and construction for solving the problem of "mousetrapping" and breaking of the rigid spine produced by perfect binding. In the Sallinen patent a soft cover is fastened to the book block by means of an independent member such that the spine part of the cover is held apart or separated and not attached directly to the spine of the book block. The independent fastening member, or a plurality of such members, in this case comprises a resiliently compressible sleeve or tube made of paper or other material which is nonpenetrable by glue. If a single tube is used, the circumference of the tube is at least twice the width of the spine of the book block and is preferably equal in length to the height of the spine. The Sallinen patent teaches the gluing of the individual compressed or flattened tube or a number of tubes on one side to the cover spine and on the other to the book block spine. The Sallinen concept also contemplates the use of a sleeve having a circumference greater than twice the width of the spine of the book block. In this form, the sleeve is also glued to the edges of the book block a short distance beyond the back edges of the first and last leaves. This expedient is also used in some cases with prior art perfect binding to obtain a stronger fastening between the cover and the book block. With the Sallinen concept, high strains normally directed at these pages on opening of the cover are thus avoided since the flexible folds in the sleeve between the cover and the first and last pages efficiently attenuate such strains. The Sallinen patent as well as the Duryea patents, however, deal only with the book block and soft cover construction and the method and order of assembling and gluing the individual preformed members. Although the tube or sleeve binding constructions of these patents create a lay-flat, resilient, durable perfect bound book, which functions like a Smyth-sewn, casebound (hard cover) book with the economy of adhesive binding, no process or machine capable of in-line use with perfect binding equipment is available for assembling such bindings. As a result, there has been no widespread commercial acceptance of this type of binding.
U.S. Pat. No. 5,078,424 to Kadish illustrates another form of binding wherein a tubular member provides the fastening means between the spine of the book block and the soft cover. The tubular member is composed of a woven plastic yarn formed preferably from polyester filaments designed to present interstices for the reception of glue. This solution is offered as an alternative to the use of paper tubes, reinforced or otherwise, which are admittedly more economically feasible for mass production of soft cover books. Although the Kadish patent suggests the feeding of covers singly into a stream to receive the tubular ribbon, no apparatus or means for accomplishing this result is disclosed and no steps are suggested for tube formation, unwinding, pulling and uniting with the moving covers. The use of a "hot knife" is suggested for separating the covers by severing the plastic tubular ribbon, but no such apparatus is disclosed. In addition to the difficulties of handling a longitudinally flexible, perhaps even elastic, woven fabric preformed tube, the prospect of cutting plastic tubes with a "hot knife" at the speeds required for efficient binding renders the approach impractical for most applications and unsuitable and inadequate for in-line commercial mass production utilizing perfect binding equipment.